We are investigating the ability of tyrosine aminotransferase induced in liver cytosol under conditions in which there is a stimulus to urea synthesis to translocate to the mitochondrial surface. In the coming year we plan to determine with specific antibody and P32 whether the enzyme which translocates to the mitochondrial surface is phosphorylated directly and if such phosphorylation is responsible for the phenomenon. Also, we will extend studies on coenzyme dissociation as the rate-limiting step in enzyme degradation to a number of other enzymes which respond in various ways to glucocorticoid hormones in addition to enzymes we have already investigated, such as tyrosine aminotransferase, tryptophan oxygenase ornithine decarboxylase, and others. BIBLIOGRAPHIC REFERENCES: M.H. Cake & G. Litwack, The glucocorticoid receptor, in Biochemical Actions of Hormones, G. Litwack (editor), Academic Press, New York, 3, 319-390 (1975). C.M. Croce & G. Litwack, Genetic approaches to enzyme induction in mammalian cells and hybrids in culture, in Biochemical Actions of Hormones, Academic Press, G. Litwack (editor), New York, 3, 23-39 (1975).